In practice, I've seen both shared app, shared DBs, and shared app, separate DBs. "Shared / separate DBs" is not actually so black and white. I recommend making

In practice, I've seen both shared app, shared DBs, and shared app, separate DBs. "Shared / separate DBs" is not actually so black and white. I recommend making your system configurable so you can dedicate DBs to a specific tenant (or group of tenants) if needed. Most of them probably won't need it...